I have a blissful smile on my face just sitting here dreaming about it all Paul.
I did my first dissertation in collage about ethics within a doomsday scenario called "Ethics, a view from the moon". I worked through a hierarchy of things that might morally require saving along each stage of a string of increasingly fundamental acts of (humanly induced) destruction, according to different and competing philosophical standpoints. It ended with a few bits of rock and a cloud of dust floating in space. The last ethical dilemma was whether a person (watching from the moon) should save these for posterity, or for sentimental reasons from an existential viewpoint.
Asteroids don't have to worry about all that stuff...
By all means preserve the bits of rock and dust for posterity , bury them somewhere on the moon , or send them into deep space via a Voyager like probe with the warning :- "Remnants of a beautiful planet , unfortunately destroyed by humankind" .
A sobering thought here ; in the late 70s the Voyager probes were launched ; after breathtaking images of the outer planets they are both heading out of the solar-system at approx. 39,000 mph .
At that velocity , Voyager 2 will be approaching the vicinity of Sirius (8.5 light years away , and a close neighbour by astronomical standards ) around the year 296,000AD !!!
Puts us into perspective !
Certainly, it's a long time off for those (erroniously) hoping that something out there might come along and sort it all out for us.
Not that they'd
anything to do with us anyway considering our past record. We'd have a flashing sign next to our planet on any space map saying "Forget it, top species in food chain very nasty!"